John Furey

Prediction of CL-20 chemical degradation pathways, theoretical and experimental evidence for dependence on competing modes of reaction

Highest occupied and lowest unoccupied molecular orbital energies, formation energies, bond lengths and FTIR spectra all suggest competing CL-20 degradation mechanisms. This second of two studies investigates recalcitrant, toxic, aromatic CL-20 intermediates that absorb from 370 to 430 nm. Our earlier study (Struct. Chem., 15, 2004) revealed that these intermediates were formed at high OH− concentrations via the chemically preferred pathway of breaking the C–C bond between the two cyclopentanes, thereby eliminating nitro groups, forming conjugated π bonds, and resulting in a pyrazine three-ring aromatic intermediate. In attempting to find and make dominant a more benign CL-20 transformation pathway, this current research validates hydroxylation results from both studies and examines CL-20 transformations via photo-induced free radical reactions. This article discusses CL-20 competing modes of degradation revealed through: computational calculation; UV/VIS and SF spectroscopy following alkaline hydrolysis; and photochemical irradiation to degrade CL-20 and its byproducts at their respective wavelengths of maximum absorption.

Theoretical predictions of chemical degradation reaction mechanisms of RDX and other cyclic nitramines derived from their molecular structures.

Analysis of environmental degradation pathways of contaminants is aided by predictions of likely reaction mechanisms and intermediate products derived from computational models of molecular structure. Quantum mechanical methods and force-field molecular mechanics were used to characterize cyclic nitramines. Likely degradation mechanisms for hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) include hydroxylation utilizing addition of hydroxide ions to initiate proton abstraction via 2nd order rate elimination (E2) or via nucleophilic substitution of nitro groups, reductive chemical and biochemical degradation, and free radical oxidation. Due to structural similarities, it is predicted that, under homologous circumstances, certain RDX environmental degradation pathways should also be effective for octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) and similar cyclic nitramines. Computational models provided a theoretical framework whereby likely transformation mechanisms and transformation products of cyclic nitramines were predicted and used to elucidate in situ degradation pathways.

Review of Magnetic Modeling for UXO and Applications to Small Items and Close Distances

Abstract Prior to 1990, UXO were generally modeled or approximated as compact, ferrous objects; the model was effectively a uniformly magnetized sphere of iron at a specified or an unknown distance from the magnetic sensor. Correlations were developed between various UXO, represented as compact masses of iron, and magnetic anomaly signature features such as maximum positive value, peak-to-peak value, and wavelength. The uniformly magnetized sphere, equivalent to a point dipole model external to the sphere, cannot account for magnetic phenomenology of actual UXO, which exist in forms ranging from approximately spherical to highly elongated, with elongations as large as 5 (ratio of length to diameter). UXO are generally ferrous, with large magnetic permeability, although some can contain aluminum or other non-magnetic metals. This paper reviews the phenomenology of models applied to simulation of UXO magnetic anomalies. The multipole expansion solution of the prolate spheroid model in earths magnetic field...

The Physical Dipole Model and Polarizability for Magnetostatic Object Parameter Estimation

The physical dipole is the next simplest model of a magnetic object beyond the point dipole model. The theory and analytical properties of the physical dipole are developed and explored, and compare favorably with alternative models, including limiting cases of prolate spheroids and other shapes. The general applicability of explicitly modeling the demagnetization properties of magnetic materials is critically reviewed, and reasons proffered to use the object polarizability instead, especially for the external field properties of most relevance. Neither the physical dipole model nor polarizability is currently used for magnetostatic parameter estimation of magnetic objects such as unexploded ordnance. It is recommended that their utility be further explored with field data.

Laboratory goniometer approach for spectral polarimetric directionality

A two meter inner diameter goniometer provides approximately 0.1° angular positioning precision for a series of spectral and polarimetric instruments to enable measurements of the directionality of polarized reflectance from soils in the laboratory, at 10° increments along the azimuth and zenith. Polarimetric imaging instruments to be mounted on the goniometer, with linear polarizers in rotators in front of each instrument, include broadband focal plane array imagers in the Visible band (Vis), Near InfraRed (NIR), Short Wave InfraRed (SWIR), and Long Wave InfraRed (LWIR) spectral bands, as well as a hyperspectral imager in the Vis through NIR. Two additional hyperspectral polarimetric imagers in the Vis through NIR, and SWIR, are to be mounted separately with angles measured by laser on the goniometer frame.

Soil polarization data collected for the global undisturbed/disturbed Earth (GUIDE) program

A key product of the global undisturbed/disturbed earth (GUIDE) program is the development of a soils database of broadband, hyperspectral, and polarized data. As a part of the GUIDE program, the U.S. Army Engineer Research and Development Center (ERDC) conducted a testing series involving a large variety of instrumentation at several sites at the Yuma Test Center (YTC) in fiscal year 2015 under the auspices of the Joint Improvised Explosive Device Defeat Organization (now the Joint Improvised-Threat Defeat Agency), generating approximately 17 terabytes of data. Most of this data, available through the ERDC, comprises hyperspectral polarimetric scientific data in the visible, near-infrared, shortwave infrared, and longwave infrared bands. As part of this testing series the performance of six handheld devices was characterized. We discuss the process of this data collection at YTC focusing on the polarimetric data, including the two handheld devices that relied on polarization for detection. Although some other polarization states discriminate soils better in some other wavelengths, for certain visible and near-infrared bands the Stokes S2 parameter provided the best discrimination.